The main obstacle Photovoltaic (PV) industry is facing at present is the higher cost of PV energy compared to that of fossil energy. While solar cell efficiencies continue to make incremental gains these improvements are so far insufficient to drive PV costs down to match that of fossil energy. Improved in-line diagnostics however, has the potential to significantly increase the productivity and reduce cost by improving the yield of the process, as proven by industry leaders. MicroXact proposes to develop a high-throughput in-line PV manufacturing diagnostic system, which will provide fast and accurate data on the spatial uniformity of thickness, refractive indices, and the film stress of the thin films comprising the solar cell as the solar cell is processed reel-to-reel. The retrieved information will provide the opportunity to detect a wide variety of processing errors, including but not limited to thickness/composition in homogeneity in any layer comprising PV device, non-uniform scribing, thin film stress, cracking and layer separation.Commercial Applications and Other Benefits The initial target application for the proposed in-line crystalline silicon and thin film manufacturing diagnostic system is the PV cell manufacturing lines with high production capacity ( & gt;10MW/year), in which the benefits of the in-line diagnostics (such as yield improvement and cost reduction) are expected to outweigh the cost of system installation immediately. In addition, low-cost system modifications will be developed to target off-line quality assurance and quality control at smaller-scale PV cell manufacturing lines.